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Method for Providing Z-Axes Connections in Printed Circuit Boards Having Homogeneous Organic Dielectrics

IP.com Disclosure Number: IPCOM000118628D
Original Publication Date: 1997-Apr-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Buth, M: AUTHOR [+5]

Abstract

Disclosed is a two-step method for providing Z-connections for plated-through holes or blind vias in printed circuit boards.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 64% of the total text.

Method for Providing Z-Axes Connections in Printed Circuit Boards
Having Homogeneous Organic Dielectrics

      Disclosed is a two-step method for providing Z-connections for
plated-through holes or blind vias in printed circuit boards.

      Z-axes connections of today's printed circuit boards are
manufactured using methods like drilling or plasma etching.
Mechanical drilling can be used down to approximately 100 &mu.m; for
the manufacture of smaller holes, the cost for the drills will be too
high if they can be manufactured at all.  Plasma techniques do have
problems concerning hole geometry and repetition.

      Therefore, a new process sequence is proposed for creating the
Z-connections in printed circuit boards.  All greater and relatively
noncritical holes or vias are manufactured using wet-chemical methods
and all small holes or vias are created by laser methods.

The general sequence is as follows:
  o  First step
     1.  mechanical or, if necessary, optical adjustment
     2.  lithographical structuring and wet-chemical etching of
         -  great vias or holes (> 60-75 &mu.m)
         -  exposure of optical adjustment marks in the circuit
             layer S1
  o  Second step
     1.  optical adjustment
     2.  lithographic structuring and laser etching of the small
          vias or holes (< 60 &mu.m)

In the following, an example for wet-etching vias in polyimide parts
of printed cir...